Blasting cartridge



pt- 22, 3 .P. A. GOLDSMITH Er AL 2,055,126

BLASTING CARTRIDGE Filed March 19, 1934 i un. I lu ll 64. JWYM Patented Sept. 2 2, 1936 {UNITED STATES BMSTING CARTRDGE Peroy Alfred Harry Goldsnitl and John Gibson Lapraik,

Faverslam,

England, assignors to Heaters Limited, London, England a. British company Application Maroh 19, 1934, Serial No. '116,360 In .Great Britain March 31, 1933 10 Claims.

This invention comprises improvements in or relating to heating compositions for use in blasting cartridges of the type wherein a charge ot condensed material (for example carbon dioxide) employed but it has now been found that a relatively slow-burning self-combustible mixture, such as is sometimes used in fireworks, and which 3 cannot be detonated, yields satisfactory results.

The present invention therefore comprises in a-blasting cartridge of the kind described, the combination of a pressure resisting container provided with a rupturable sealing device, means (for 3 example a quantity of compressed carbon dioxide) within 'the container to yield gases under pressure adequate to rupture the scaling device on heating and a heating mixture consisting of 'an oxygen-carrying salt (for example potassium 5 perchlorate) and a crystalline Organic fuel.

Mixtures of oxygen-carrying salts and crystalline Organic fuels such as sugar are commonly used in fireworks. They are characterized by burning slowly and evenly under atmospheric 0 pressure.

One of thefuels which has been found Satisfactory for use according to the present invention is salicylic acid. This is an Organic acid and other stable crystalline Organic acids which act 35 as fuels can also be employed such, for example as benzoic acid, but Organic acids or other fuels which are themselves unstable or liable to react with other constituents of the mixture or notable for rapidity of combustion or detonation would not be suitable for the purpose in view. Thus picric' acid is not suitable. In addition, the iuel must not be soluble in liquid carbon dioxide ii this is employed in the rupturable container and preferably it should not be hydroscopic. We

" have found that although a mixture of potassium perchlorate and 'salicylic acid is slow burning under atmospheric conditions it is sumciently quick burning when immersed in carbon dioxide under pressure to act as an effective heater tor i0 this type of blasting charge.

Another type of fuel which can be employed consists of a crystalline carbohydrate sch'as cane sugar. In some cases the salicylic or like acid and sugar may be used in admixture with one (CI. nie-6 lies in the fact that such mixtures are easily made in an ordinary mixing machine and filled into paper containers under a predetermined degree o! pressure. Every crystalllne mixture has a natural density to which it will pack it merely filled into containers and tightly tamped in place, but by packing under pressure in a filling machine the crystals can be crushed together to give a higher density. This aifords an easy way of exactly controlling the rate of burning by regulating the degree of compression of the charge. Hitherto in some cases resinous fuels have been used as the heating mixture but such fuels, although they may in certain cases give a relatively slow burning charge, do not permit of equally easy control of the rate of burning or mixture of the ingredients, compared with the crystalline mixtures herein recommended.

The finished mixture has also been found to be insensitive to shock and friction, consequently it can be made in fairly large quantities with considerable safety. This is an advantage over mixtures used in' connection with carbon dioxide blasting devices in which dry aluminum forms a constituent part of the ingredients, which are sensitive both to shock and friction.

The manufactured powder is stable', safe to handle and owing to the non-hygroscopic qualities of the ingredients used it is not affected byclimatic changes and does not deteriorate during storage.

As an aid to uniformity and controllability of the heating mixture it has been found that the addition of a small quantity of a non-drying Vegetable oil such as for example castor oil, has beneficial results. Hitherto the use of such a substance has been deprecated owing to the claim that carbon dioxide acted upon castor oil, but it has been determined that carbon dioxide has no effect on castor oil when this is used in conjunction with the heating composition of the perchlorate salicylic type. e

In cases where sugar is used, should the mixture be found to be too slow in burning or liable to incomplete combustion it is found beneflcial to include with t? e heating mixture a small quantity of a metallic oxide (for example lead oxide) Lead oxide also acts to some extent as a lubrlcant in the mixture.

In the accompanying drawing:-

Figures 1 and 1A represent a blasting ca'rtridge in accordance with the invention;

Figure 2 is a diagrammatic representation of a. filling machine.

Referring to Figure 1, H is a container made of steel and which may be for example 1%" in external diameter and 36" long. It is closed at one end by a screwed plug l2 which is drilled centrally at l3 and provided with gas outlet ports M. The plug' l2 serves to hold in place a rupturable steel scalin disc li on a seting Nj.

At the other end of the cartridge there is a screwed plug !1 which supports a perforated metallic tube a in the container Il. The tube l8 receives a paper cylinder !9 which contains a heating mixture and a powder !use 20 to ignite the same. trio leads 2l, 22, one of which is connected to a metallic end cap 23 and thence to the body of the container, while the other passes through a wooden plug 24 to an insulated terminal 25. The body of the container is provided with a brass ferrule 26 in electrlcal connection with the body itself and with a second brass ferrule 21 which is insulated from the body but electrically connected to-the terminal 25. Thus a two-pin plug inserted in the ferrules 26, 21 will serve to convey electric current to the fuse 20 and ignite the heating charge. The cartrldge is provided with an end plug 28 which serves to seal a charging conduit 29, whereby carbon dioxide may be charged into the container under high pressure. Cartridges of the type described are well known in themselves, but according to the present invention they are combined with special heating mixtures in the paper-container i@ which have peculiar advantages in this combination.

Referring to Figure 2, this is a diagrammatic illustration of a well known type of filling machine. A hopper 30 receives a mixture which is to be fed into the paper tubes l such as are illustrated in Figure 1. At the bottom of the hopper 30 there is a brass tube 32 co-axial with the hopper and forming a downward prolongation thereof, the size of the tube 32 being such that the paper tube i@ can be slid over it. The paper tube or container !9 rests upon a table 33 mounted for reciprocating movement upon a stem 34 which works in bearings 35. A counterweight 35 is connected by a cord s'i to the stern 34 and serves to raise the table with a predetermined upward pressure, the amount of which can readily be regulated by varying the counterweight. Within the tube 32 is a filling worm 33 on a stem 39 driven by bevel gearing 40, ti from a, pulley 62. Appropriate 'means for starting and stopping the rotation of the worm 38 at the will of the operator are provided but are not illustrated in the drawing.

The hopper 30 is fllled'with the heating mixture desired and the containers IS are filled with the mixture under a -predetermined pressure which is regulated bythe counterweight 36. The degree of this pressure regulates the amount of compression of the mixture and its density.

The following are examples illustrating the specific instances' of the use of the invention:-

These parts are taken in a flnely powdered crystalline form such, for example, as would pass a screen having meshes to the linear inch and are mixed in an ordinary mixing machine suchas is used for mixing gunpowder. They are then charged into the paper container |9 as already described. The container IS is forced downwardly as the filling worm 38 presses the crystalline mixture into it from the hopper 30 and the counterweight 36 to the table ensures a predetermined degree of compression. This method of charging containers with pow'ier is well known From the fuse 20 there are two elec-' aosaae in the explosive industry. The degree of compression employed should preferably be such that in containers having an internal diameter of half an inch and a length of nine and three-quarter inches of space occupied by the mixture there will be accommodated from 41-45 grams of themixture. i This corresp'onds to an overall density of the crystalline mixture of about 1.24 to 1.33; The mixture is ignitable by a low tension fivegrain powder fuse.

The mixture described in this example if used in a container having an internal diameter of half an inch as above described and made of a weight of 45 grams is adapted for use in a carbon dioxide cartridge having an external diameter of 1%" and 36" long. This will contain 1 lb. 2 ozs., of compressed carbon dioxide and be sealed with a disc 7/64th of an inch thick.

As an alternative to lead oxide the oxides of iron or copper can be added to the mixture, especially where the percentage of potassium perchlorate chosen is a low one, as they provide a certain amount of oxygen in the charge.,

Example II 4 Parts by wt. in 10@ Potassium perchlorate 622 Cane sugar lili Crystalline Salicylic acid 26!? 4 These ingredients are mixed and charged inte a cartridge as described in Example I and, used 'in similar quantity, the heater mixture will give similar results. V

4 Example EH Parts by wt. in 106' Potassium perchlorate '31.5 Crystalline Salicylic acid 28.5

This mixture is charged and used as already" described for Example I.

Example IV Potassium perchlorate 79 to 71% Salicylic acid 19 to 27% Castor nil 2 The above ingredients are mixed in an ordinary mixing machine consisting of a drum fltted with revolving blades. The finished composition, which may be likened to meal flour from which no dust rises is then filled mechanically into paper tubes of a diameter inch, the tubes afterwards being fltted with an electric low tension powder fuse. The weight of the mixture used may be, say 43 to45 grams and density preferably 1.36 to 1.44.

The complete heating element is then introduced into a, carbon dioxide container in the known manner, the fuse being electrically connected to it.

Example V In addition the following compositions have proved eflective and may be used as alternatives when required:

Parts by wt. Potassium perchlorate 79 to 71% Salicylic acid 14 to 23% Cane sugar 4% Castor oil 2% We claimzv 1. In a blasting cartridge,-a oombination of a pressure-resisting oontainer, a rupturable scaling device therei'or, means within the container to yield gases under pressure adequate to rupture the seaiing device on heating. a heating mixture consisting oi! an oxygen-carrying salt and crystalline salicyclic acid and means for igniting the heating mixture. I

2. In a blasting cartridge. the oombination ot a pressure-resisting container. a rupturab'le seaiing device therefor, carbon dioxide within the container to yield gases under pressure adequate to rupture the scaling device on heating. a heating mixture consisting oi' an oxygen-carrying salt and crystalline salleyclic acid and means !or igniting the heating mixture e i? i 3. In a blasting cartridge, the comhination of a pressure-resisting oontainer, a rupturable scaling device therefor, means within the oontainer to yield gases under pressure adequate toruptnre the scaling device on heating, a heating mixture consisting of an oxygen-carrying salt and a crystalline organic uel, said mixture being compressed to have .an overall density greater than the natu'al packing density of the mixture and means for igniting the heating mixture.

4. In a blasting cartridge, the combination of a pressure-resisting container. a rupturable scaling device therefor, means within the oontainer to yield gases under pressure adequate to rupture the sealing device on heating, a heating mixture consisting of potassium perchlorate and saiicyiic acid compressed so as to have an overall density of not less than 1.36 and means tor igniting the heating mixture.

5. In a blasting cartridge, the combination of a pressure-resisting container, a rupturable sealng device thereior. means within the container to yield gases under pressure adequate to rupture the seaiing device on heating, a heating mixture consisting of 'postassium perehiorate and a carbohydrate and compressed so as to have an overall density not less than 1.24 and means for i igniting the heating mixture.

6. In a blastin'g cartridge, the oombination of a pressure-resisting container. a rupturable sealing device therefor, carhon dioxide within the container to yield gases under pressure adequate to rupture the sealing device on heating. heating mixture consisting of potassium perchlorate and salicylie acid compressed to have an overall density not less than 1.36 and means !or isniting the heating mixture.

7. In a blasting cartridge, the combination of a pressure-resisting container, a rupturable sealing device thereior, carbon dioxide within the container to yield gases under pressure adequate to rupture the sealing device on heating, a heating mixture eonsisting o! potassium perchlorate and a carbohydrate compressed so as to have an overall density ot not less than 1.24 and means for igniting the heating mixture.

8. In a blasting cartridge; the combinationoi a pressure-resisting container provided with a rupturable sealing device and means within the oontainer to yield gases under pressure adequate to rupture the sealing device on heating, a heating mixture within the container which is slowburning under atmospheric conditions, said heating mixture comprising an oxygen-carrying salt in admixture with a crystalline Organic acid.

9. In a blasting Cartridge, the combination of a pressure-resisting container provided with a rupturabie sealing device. carbon dioxide within the container to yield gases under pressure adequate' to rupture the sealing device on heating a heating mixture within the container which is slowburning under atmospheric conditions, said heating mixture comprising an oxygen-carrying salt in admixture with a crystalline Organic acid.

10. In a blasting cartridge, the oombination of a pressure-resisting contalner provided with a rupturable sealing device and earbon dioxide within the container to yield gases under pressure adequate to rupture the scaling device on heating. a heating mixture within the .container which is slow-burning under atmospheric conditions, said heating mixture comprising an oxysen carrying salt in admixture with salicylic acid.

PERCY ALFRED HARRY GOLDSMITH.

JOHN GIBSON LAPRAIK. 

